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// Copyright (c) 2022 PlanetScale Inc. All rights reserved.
// Package protohelpers provides helper functions for encoding and decoding protobuf messages.
// The spec can be found at https://protobuf.dev/programming-guides/encoding/.
package protohelpers
import (
"errors"
"fmt"
"io"
"math/bits"
)
var (
// ErrInvalidLength is returned when decoding a negative length.
ErrInvalidLength = errors.New("proto: negative length found during unmarshaling")
// ErrIntOverflow is returned when decoding a varint representation of an integer that overflows 64 bits.
ErrIntOverflow = errors.New("proto: integer overflow")
// ErrUnexpectedEndOfGroup is returned when decoding a group end without a corresponding group start.
ErrUnexpectedEndOfGroup = errors.New("proto: unexpected end of group")
)
// EncodeVarint encodes a uint64 into a varint-encoded byte slice and returns the offset of the encoded value.
// The provided offset is the offset after the last byte of the encoded value.
func EncodeVarint(dAtA []byte, offset int, v uint64) int {
offset -= SizeOfVarint(v)
base := offset
for v >= 1<<7 {
dAtA[offset] = uint8(v&0x7f | 0x80)
v >>= 7
offset++
}
dAtA[offset] = uint8(v)
return base
}
// SizeOfVarint returns the size of the varint-encoded value.
func SizeOfVarint(x uint64) (n int) {
return (bits.Len64(x|1) + 6) / 7
}
// SizeOfZigzag returns the size of the zigzag-encoded value.
func SizeOfZigzag(x uint64) (n int) {
return SizeOfVarint((x << 1) ^ uint64(int64(x)>>63))
}
// Skip the first record of the byte slice and return the offset of the next record.
func Skip(dAtA []byte) (n int, err error) {
l := len(dAtA)
iNdEx := 0
depth := 0
for iNdEx < l {
var wire uint64
for shift := uint(0); ; shift += 7 {
if shift >= 64 {
return 0, ErrIntOverflow
}
if iNdEx >= l {
return 0, io.ErrUnexpectedEOF
}
b := dAtA[iNdEx]
iNdEx++
wire |= (uint64(b) & 0x7F) << shift
if b < 0x80 {
break
}
}
wireType := int(wire & 0x7)
switch wireType {
case 0:
for shift := uint(0); ; shift += 7 {
if shift >= 64 {
return 0, ErrIntOverflow
}
if iNdEx >= l {
return 0, io.ErrUnexpectedEOF
}
iNdEx++
if dAtA[iNdEx-1] < 0x80 {
break
}
}
case 1:
iNdEx += 8
case 2:
var length int
for shift := uint(0); ; shift += 7 {
if shift >= 64 {
return 0, ErrIntOverflow
}
if iNdEx >= l {
return 0, io.ErrUnexpectedEOF
}
b := dAtA[iNdEx]
iNdEx++
length |= (int(b) & 0x7F) << shift
if b < 0x80 {
break
}
}
if length < 0 {
return 0, ErrInvalidLength
}
iNdEx += length
case 3:
depth++
case 4:
if depth == 0 {
return 0, ErrUnexpectedEndOfGroup
}
depth--
case 5:
iNdEx += 4
default:
return 0, fmt.Errorf("proto: illegal wireType %d", wireType)
}
if iNdEx < 0 {
return 0, ErrInvalidLength
}
if depth == 0 {
return iNdEx, nil
}
}
return 0, io.ErrUnexpectedEOF
}
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